RE: Disabling spanning tree

STP cannot be operational without BPDUs.

BPDU filter effectively disables spanning tree on a port because it filters
in AND out. Is it a turn off knob? No. Is it a trick? Yes.

tv

From: Jonathan Greenwood II [mailto:gwood83_at_gmail.com]
Sent: Thursday, April 16, 2009 1:48 PM
To: Tony Varriale
Cc: ccielab
Subject: Re: Disabling spanning tree

STP is still operational as the port still must transtion through the
various port states, in this case you have portfast which is a STP feature.
That's still STP wouldn't you agree regardless of BPDU's being filtered or
not? I don't have access to a switch at the moment, but I agree with your
test. My argument is that you can't disable STP on a per port basis.

Jonathan Greenwood II

CCIE #22744

On Thu, Apr 16, 2009 at 11:40 AM, Tony Varriale <tvarriale_at_flamboyaninc.com>
wrote:

The question mentions nothing about TCNs or port flapping.

How about config BPDUs? Put it up in a lab...

Here's a quick example in production for you that has portfast but not
bpdufilter:

interface GigabitEthernet9/12
 switchport
 switchport access vlan 12
 switchport mode access
 spanning-tree portfast

xyz#sh spanning-tree int g9/12 d
BPDU: sent 10566749, received 0

Spanning tree is not disabled. Period.

Here's one in production with bpdufilter:

xyz#sh run int g1/1
Building configuration...

Current configuration : 171 bytes
!
interface GigabitEthernet1/1
 switchport access vlan 201
 switchport mode access
 spanning-tree portfast
 spanning-tree bpdufilter enable

xyz#sh spanning-tree int g1/1 d
BPDU: sent 0, received 0

No BPDUs sent or received. If both are none, would you say it's
participating in spanning tree?

tv

-----Original Message-----
From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of

Jonathan Greenwood II
Sent: Thursday, April 16, 2009 1:25 PM
To: Tharak Abraham
Cc: Salah ElShekeil; ccielab
Subject: Re: Disabling spanning tree

With portfast TCN BPDU's will not be sent if a port goes up or down thats
configured for portfast. FYI

Jonathan Greenwood II
CCIE #22744

On Thu, Apr 16, 2009 at 11:17 AM, Tharak Abraham
<tharakabraham_at_gmail.com>wrote:

> Spanning tree would be still be active even if you enable portfast and
> bpdus will be sent out !
>
> bpdu filter on access ports will stop all kinds of bpdu's and hence that
> should be more appropriate in this context !
>
>
> Tharak Abraham Luke
>
>
> On Thu, Apr 16, 2009 at 8:04 PM, Jonathan Greenwood II <
> gwood83_at_gmail.com> wrote:
>
>> I agree with Mr. West. They are looking for portfast based on your
>> question.
>>
>> HTH
>>
>> Jonathan Greenwood II
>> CCIE #22744
>>
>> On Thu, Apr 16, 2009 at 10:17 AM, Salah ElShekeil <
>> salah.elshekeil_at_gmail.com
>> > wrote:
>>
>> > Dear all,
>> >
>> >
>> >
>> > how to disable spanning tree on an interface without using "no spanning
>> > tree" command?
>> >
>> >
>> >
>> >
>> >
>> > Salah
>> >
>> >
>> > Blogs and organic groups at http://www.ccie.net <http://www.ccie.net/>
>> >
>> > _______________________________________________________________________
>> > Subscription information may be found at:
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>> >
>> >
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>> >
>> >
>> >
>> >
>>
>>
>> --
>> Jonathan Greenwood II
>> CCIE #22744
>>
>>
>> Blogs and organic groups at http://www.ccie.net <http://www.ccie.net/>
>>
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--
Jonathan Greenwood II
CCIE #22744
Blogs and organic groups at http://www.ccie.net <http://www.ccie.net/>